Torch for welding thermoplastic material



.Aprii 3, 1945. w. M. PHILLIPS JR TORCH FOR WELDING THERMOPLASTIC MATERIAL Filed April 16, 1945 INVENTOR. WII/Iam M. Phi/[119g Jr. B I

flitofnl0- Patented Apr. 3, i945 2.372.737 TORCH FOB WELDING THERMOPLASTIC MATERIAL William M. Phillips, In, The Udyllte corpora poration of Delaware Detroit, Mlela. aulgnor to tlon, Detroit, Mich, a cor- Application April is, 194:, Serial No. 483,365 2 Claims. (01. 154-42) This invention relates to atorch useful in the welding of thermoplastic materials according to the method described in the copending application of Gunnar Lindh and William M. Phillips, Jr., Serial No. 476,228, filed February 1'7, 1943, now Patent No. 2,367,725, dated January 23, 1945.

It is the object of this invention to produce a simple tool which materially facilitates and expedites the welding of thermoplastic materials.

Fig. 1 is a perspective view showing the tool in operative position during the welding operation.

Fig. 2 is a longitudinal sectional view through the tool.

Figs. 3 and 4 are sections along the lines 3-3 and 4-4 of Fig. 2.

The tool includes a torch for generating and directing a heated gaseou blast or jet against the surfaces to be welded to bring them to their welding temperature. For purposes of description and not by way of limitation, the torch is shown as comprising a tube I preferably of refractory material, one end of which is constricted as at 2.

and has afilxed thereto the nozzle 3. A resistance heating element 4, such as a coil of nickel-chrome (Nichrome) wire, is mounted within the tube I.

The heating element 4 is provided with leads I and I through which the current is conducted to and from the heating element. Lead I is positioned within the coil 4 and is encased in a tube 1 of refractory material which prevents the lead from short-circuiting the coil. The refractory tube I is housed in a steel shell 8 provided with a closure 9 at one end through which leads 5 and I pass. The other end of shell 8 is closed down in air-tight relation with end 2 of refractory 35 tube I.

Tube I is provided with a plurality of circumferentially spaced orifices III adjacent one end and the opposite end of casing 8 is provided with a gas inlet 'II connected by means of conduit II with a source of gas (not shown) under pressure. The gas flowing through line I! is preferably air or one of its component gases, or can be any other suitable gas which is inert when heated with respect to the thermoplastic material being welded. The gas, such as air under pressure, flows through line l2, enters the passageway II between tubes I and '8, and flows in the direction of the arrow. on the outside of tube I. The air then passes through orifices III and reverses its direction of flow through tube I and about the heating element 4 where it is heated to the desired temperature preparatory to being discharged from nozzle I against the surfaces to be welded to bring them to their welding temperature.

a guide for locating the nozzle in position with respect to the sheets to be welded so that the hot gas blast will be properly directed.

For welding thermoplastic sheets II and II together there is provided a weld strip II' of similar lo thermoplastic material. The tube is provided with a guide 2| through which the strip II is fed during the welding operation. The guide 2| is amxed at its rear end to the casing I by the bracket 22 and at its forward end is welded to 15 the metal conduit II as at- 23. Bracket 22 also serves as a support for the metal tube I2. Tube If is connected by means of a flexible conduit 24 with a source of air under pressure. The guide II i provided with channel portions II and II an adjacent its rear and front ends through which the strip II is threaded and guided as it is fed down on the surfaces to be welded. A pressure roller 21 is rotatably mounted upon one end of a spring arm II, the other end 28 of which is 8b as fixed to the guide 2|. Strip II feeds under roller 1 I! which bears down upon strip 20 with sufilcient spring pressure to press it into welding contact with the adjoining surfaces of sheets II and II.

In operation the electrical current flowing through resistance element 4 brings the same to" the desired temperature. The heating element 4 heats the air flowing through tube 1 in a counter-current direction to that flowing through tube I without tube I. This hot air blast is directed from nozzle 3 against the upper sur. faces of thermoplastic sheets II and II and the under surface of strip 20 to melt these surfaces or bring them to welding consistency. Afterthe sheets II and II are placed edge to edge in abutting relation, the leading edge II of strip 20 is welded to sheets II and "and the tool then backed away graduall as the under surface of strip 20 and the upper adjacent surfaces of sheets II and II reach their welding temperature and consistency. The roller 21 applies welding pressure upon strip III and the adjacent surfaces of sheets II and I9. Roller I4 helps to hold the sheets down flat so that the heat from the nozzle I will be equally applied or distributed. Rollers I4 and I! cooperate to enable the operator to hold the torch at aconstant and proper angle with respect to the surfaces being welded.

Rollers I4 and II, of course, roll along on ppersurfacesofsheets IIand II.

to This tool or torch is useful for welding thermoassets? numerous well known organic plasticizers such as tricresyl phosphate or dioctyl phthalate. Saran F425," a trade name for a copolymer of vinylidene chloride and vinyl cyanide, Vinylite,"-

a. trade name ior a copolymer of vinyl chloride and vinyl acetate, polystyrene (polymerized styrene), polymers or vinyl benzene, polymers or vinyl chloride. polymers of vinyl acetate.

The temperature of the gas blast can be regulated by regulating the speed or amount of flow oi the gas or air by the heating element 5 and by regulating the amount of current flowing through the heating velement.

From the above it is evident that the above tool will considerably expedite the welding together of thermoplastic sheets and facilitate the obtaining of a uniform weld throughout the area or length of material being welded.

I claim:

1. A welding tool useful in welding two sheets oi thermoplastic material together when said sheets are placed edge to edge, comprising a torch having a nozzle adapted to direct a hot gaseous blast against the suriaces of the sheets adjacent said joint as the torch is moved along said joint, and guide means associated with said torch and we ting adiscent said nozzle for guiding a weld strip into said gaseous blast and over said it to weld the two sheets and strip of thermoplastic material together as they reach their welding temperature, and pressure means positioned over said weld strip for pressing the same into welding relation with the said sheets over Joint while the surfaces or said strip and sheets are at welding temperature.

2. A welding tool useful in welding two sheets of thermoplastic material together when said sheets are plecededge to edge, comprising a torch having a nozzle adapted to direct a hot gaseous I blast against the surfaces of the sheets adjacent said ioint as the torch is moved along said joint, and guide means associated with said torch and tel-sting adjacent said nozzle for guiding a weld strip into said gaseous blast and over said joint to weld the two sheets and strip of thermoplastic material together as they reach their welding temperature, pressure means positioned over said weld strip for pressing the same into welding relation with the said sheets over said joint while the surfaces of said strip and sheets are at welding temperature, a roller support for the said torch, said roller support being adapted to support the torch inclined with respect to the surfaces so as to direct the hot blast against said surfaces to be welded and apply rolling pressure to the surfaces on both sides of the joint to hold the same iiat and in juxtaposition during welding.

M. I 1 JR. 

